Tell them the car has shock absorbers to dampen the suspension motion, plus it has springs to support the car. They can't have it both ways, a spring is a spring (whether it is made of steel coils or of an air bladder) and a shock is a damper. The two perform different functions.
Plus, you are taking a service manager's word over that of the contract provider's - and I recall that the contract might exclude shocks but it does not exclude springs. Your guy is not informed, I guess. We faced this with allroads all the time. If he worked on a fancy, loaded Navigator/Expedition with air springs and shocks and had a warranty claim on a spring, I bet he would find a way to bill it.